Control for selective ice cuber and crusher



April 10, 1956 w. H. FlTZNER CONTROL FOR SELECTIVE ICE CUBER AND CRUSHER Filed June 27, 1952 2 Sheets-Sheet l IN V EN T 0R.

NILLIAMH FITZNEH awlz MW *1 Jen-'2' ATTORNEY April 0, 1956 w. H. FITZNER 2,741,096

CONTROL FOR SELECTIVE ICE CUBER AND CRUSHER Filed June 27, 1952 2 Sheets-Sheet 2 FIG. 2

JNVENTOR. WILLIAMH'. FITZNER BY 83 W W ATTORNEY United States Patent CONTROL FDRSELECTIV E ICE CUBER AND CRUSHER Wiliiam H. Fitzner, Louisville, Ky., assignor to Henry Vogt Machine Company, Louisville, Ky., a corporation of Kentucky Application June 27, 1952, Serial No. 295,885

22 Claims. (Cl. 62-4) The present invention relates to a tube ice machine of the type which is capable of selectively-producing crushed ice or cube ice, and relates in particular to an automatic control arrangement for such a machine which will keep both the storage bins of the machine filled to the proper 9 level with cube and crushed ice respectively.

in the preferred embodiment an alternatively operated crusher and cuber cooperates with the freezer in the thawing phase to produce crushed ice or sized ice as required. When the machine is set for automatic operation it will produced sized ice as long as the sized ice storage bin is not full, and when the sized ice storage bin is full the machine will produce crushed ice until the crushed ice storage bin is filled. However, if the sized ice storage bin becomes depleted the operation will shift over to making sized ice. This preference for making sized ice can, of course, be changed to a preference for making crushed ice. The machine also embodies a manual selector by which the operator can cause the machine to produce sized ice or crushed ice as he desires.

Ordinarily it is preferred to produce thinner wall ice 3 masses or bodies when crushed ice is desiredand. the apparatus embodies an arrangement for stopping the freezing phase when ice masses of the proper thickness for the subsequent severing operation are formed. Thus, for example, if the machine is set for producing thick wall ice masses for sized ice, and the controls are shifted toproduce crushed ice, the machine will complete the freezing and sizing operations on the ice started, but will shift to crushed ice on the next operation. However, if the machine is set for producing thin ice masses and the control is shifted from crushed to sized ice, the freezing period will be lengthened automaticaliy, and sized ice willbe produced.

The invention will be here described in connection with such a machine by way of example in connection with the accompanying drawing wherein:

Figure l is a schematic view and wiring diagram showing the operation of the invention, and

Figures 2 and 3 are wiring diagrams showing various conditions ofthe electrical apparatus and circuits.

Referring to the drawing, a reverse cycle refrigerating apparatus is diagrammatically included and comprises a tube type evaporator 1, a compressor 2 operated by a motor 3, with a conduit 4 having a solenoid valve 5 therein between the evaporator and the compressor inlet; a condenser-receiver 6, a conduit 7 having a solenoid'valve 8 therein between the compressor outlet and the condenser; a conduit 9 having a solenoid valve 11 therein between the condenser-receiver and the evaporator to supply liquid refrigerant to the evaporator; a bypass conduitlZ having a solenoid valve 13 therein between the condenserrcceiver and the compressor inlet; and a bypass line 14 with a solenoid valve 15 therein between the compressor outlet and the evaporator. Water. is supplied to the water tubes of the evaporator by a pump 17 controlled by a motor 18. This apparatus operates in known manner, for example, as described in the application of Henry V.

Heuser, Serial No. 111,047, filed August 18, 1949, now abandoned, or Jesse D. Williams, Jr., Serial No. 95,557, filed May 26, 1949, now Patent No. 2,618,129, or in any other suitablemanner, to draw gas from the condenserreceiver, compress it, and supply it to the evaporator during the thawing phase of operation. In this phase valves 5, 8, and 11 are closed and valves 13 and 15 are open. in the freezing phasevalves 5, 8, and 11 are open and valves 13 and 15 are closed, to allow the compressor to draw gas from the evaporator and supply compressed gas to the condenser to be liquefied, the liquefied refrigerant being supplied to the evaporator through pipe 9. In the freezing phase rods of ice are formed in the tubes in the evaporator, and during the thawing phase these rods are released and fall through the tubes to a severing device.

A severing or reducing device 19 below the evaporator is operated by a reversible motor 21 through a drive belt. The severing. or reducing device selectively makes cubed or crushed ice and may be or" any desired construction, the one illustrated, by way of example, being disclosed in the application of Heuser and Fitzner, Serial No. 177,388, filed August 3, 1950, now Patent No. 2,648,203, and operates in one direction of rotation to sever the ice rods into sized pieces or cubes; and in the opposite direc tion of rotation to produce crushed or broken ice. When the ice is discharged from the tubes and the severing device 19 is operated to produce sized or cube ice, the cube ice drops on the rotating plate 22 and is directed by deflector 23 to a chute 24 leading to a cube ice storage bin 25. When the'severing device is operated to produce crushed ice, the crushed ice drops on the plate 22 rotating in the opposite direction, and is directed by deflector 23 to a chute 26 leading to a crushed ice storage bin 27. The storage bins 25v and 27 each contain actuating means, 28, 29'for switches 31 and 32 respectively. The actuating means illustrated by way of example are temperature responsive members located at a suitable level in the storage bins and arranged to open switches 31, 32 when the accumulated ice in the binsapproaches orcontacts these temperature' responsive members respectively. However, any other suitable type of control members responsive to filling or emptying'of the'respective bins may be employed to actuate the-switches 31, 32.

The freezing phase is terminated when a suitable thickness of ice is formed on the walls of the tubes in the evaporator. The terminating control means thus may be operated by time, pressure in the evaporator, or any other suitable variable function related to the thickness of ice formed. In the drawings there is illustrated a pressure operated switch 33 at the evaporator which is closed when the pressure falls to a'suitable value, as for example fifteen pounds per square inch, and the closing of this switch is employed to terminate the freezing phase when ice rods of suitable thickness to be cut to sized lengths have been produced. A second prcssure'operated switch 34 which is closed when the pressure fal s to, for example, twentyone pounds per square inch, is employed to terminate the freezing phase when thinner wall ice rods suitable for making crushed or broken ice have been formed. The control apparatus includes a selector relay 35 which selects which of theswitches 33 or 34 shall terminate the freezing phase, and as will hereinafter appear (the nonselected switch being cut out of the circuit), the closing of switch 33 or 34, as the case may be, terminates the freezing phase a and starts the thawing phase.

0 so that the opening of any of these switches will interrupt the current. The safety switches are of known construc- V ation at the start of the freezing cycle.

. by switch 7 4.

tion and may be operated bye diaphragm subject to the pressure in the lines 4 and 7. An abnormally low pressure in line 4 opens switch:36, and switch 36 isopened by an abnormally high pressure in line 7. The safety switches are provided to shut down the machine in the event of abnormal conditions encountered in operation,

' while manually operated main switch 37 controls the connection to line 38 and thus controls the starting or stopa ping of the entire apparatus.

1 52 between the main wire 3% and the coil of relay 41.

This switch is operated by the timer motor 4810 open for a moment and thus break the electrical circuits of all the apparatus connected to wire 52. A switch 53 'which is normally closed, also is operated by the timer motor to open for a moment and thus deenergize the timer motor. The timer is of well known construction and need not be described in further detail. The control system includes a phase control relay 54 which shifts the operation of the refrigerating system to the thawing 'or thefreezing phase in response to operation of switches 33 or 34 as required; the selector relay 35; and a holding relay 55 for the selector relay. Other control members will be described as the explanation proceeds.

In Figure l the apparatus is shown on automatic oper- Phase control relay 54 is deenergized and is in the freezing phase position, and a lead 56 from main conductor 39a (through wire 38) passes to switchfcontacts 57f controlled by relay goes to pump motor 18, the return lead 61 connecting by lead 62 to main relay operated switch 47. A wire 63 from wire and contacts 57 leads to solenoid valve 8, and

"has branches 63a and 63b connected to solenoid valves 11 and 5 respectively. A common return line 64 connects to lead 62 and thence to main switch47 of relay 41, and the return leads 64a and 64b of valves 8 and 11 connect thereto. Thus, valves 5, 8 and 11 are held open and the pump is being driven to supply water to the tubes in the evaporator; When the phase control relay 54 is energized and assumes the thawing phase position shown in Figure 2, current travels by wire 56 through terminals 652 and by wires 66, 67 to solenoid valve 13, with a branch 67a going to solenoid valve '15, to energizethese solenoids'and open the respective valves to start the thawing phase. These solenoids have return lines 68a and 68b connecting with line 64 to switch 47. At the same time the opening of contacts 57f deenergizes pump 17 to stop water flow, and deenergizes valves 5, 8 and 11 to allow them to close.

Switch 33, which terminates the freezing phase when ice cubes are to be made, is connected by wire 69 to switch contacts C controlled by switch 70 operated by relay 35, the contacts connecting by wire 71 to wire 38. A wire 72 from switch 33 connects to relay 54 by wire 67, and to timer 48 by wire 78, the circuits being completed through wire 64 to switch 47. Thus, with selector relay 35 energized the closing of switch 33 energizes thephase control relay 54 to start the thawing phase and energizes timer 48 which delimits or terminates the thawing phase. Referring to Figure 3, when relay 35 is deenergized, the switch 34 is connected by wire 73 to contacts B controlled In this position switch 33 is electrically inoperative, and the closing of switch 34 energizes phase control relay 54 and the timer 48. Thus,'relay 35 selects the freezing time by selecting whether switch 33 or switch 34 shall start the thawing phase.

Reversible motor 21 has a starting coil 75, and the operated switch 58; and a lead 59 from the contacts 57 .direction of rotation of motor 21 is determined by the direction of current through the starting coil. After the motor starts this coil is cut out of the circuit in known manner by a centrifugal switch or the like (not shown). a

Switches 70, 76 and 77'determine the direction of current through coil 75. With relay 35 energized, when relay 54 is energized current flows by wire 56 through switch 651, by wires 72 and 78 to switch 77 at the a con-. 7 tacts, through wire 79 to coil'75, by wire 8% to switch 76 i in position g, and by wire 62 to switch 47. At the same time motor 21 is energized through wire 81. When'relay 35 is deenergized and relay 54 is energized as shown in Figure 3, current, flows by wire 56 through switch 6 5: by wires 72, 78 to switch 79 at d position, throughwire 8%) to coil 75 and through wire 79 to switch 77 at the 1 position, then by wire 62 to switch 47. Thus it will be sec-n that selector relay 35 not only determines whether switch 33 or 34 shall terminate the freezing cycle, but it also determines or selects the production of ice cubes or crushed ice.

The manual selector switches 82 and 83 provide a manual control for the selector relay 35 to determine whether the machine shall'produce sized ice'or crushed ice, and when both switches 82 and 83 are closed (as shown 7 in Figures 1 and 3) the bin switches 31 and 32 automatically control the selector relay 35 to determine whether the machine shall produce sized ice or crushed ice. The machine as illustrated favors the production of sized ice, but by an interchange of switches and 32 and their control members the preference can be shifted V V to making crushed ice. Referring to Figure'l which shows switches 82, 83 closed, switch 31 of the cubed ice bin closed, and switch 32 of the crushed ice bin open,

the energizing circuit of relay 35 is completed from wire 7 and wire 92. Thus, it willbe seen that the operating circuit and the holding circuit for each relay 35,. 55 and 41 passes'through switch 49 controlled by the timer, so the opening of switch 49 by the timer at the end of the thaw ingrphasc deenergizes these relays and the opening of relay switch 47 by deenergization of relay 41 deenergizes all other electrical apparatus. However, as switch 49 is immediately closed again, the relay 41 is immediately energized (providing the switches 31, 32, S2, or 83 are in energizing position) and the proper operating cycle of the apparatus is repeated.

. When switch 31 is open and switch 32 is closed, as shown in Figure 3, the relay 35 cannot be energized, and assumes the position shown in Figure 3. is energized through switch 32 by wire 94, and as previ ously described, deenergized relay 35'holds switches 76, 77 in position to operate the motor 21 in crushing direction.

The operation of the entire apparatus now will be described with the apparatus on automatic operation position as shown in Figure l. The closing of switch 37 starts the operation. As freezing progresses in the evaporator switch 34 closes, but is 'in a dcenergized circuit. Then when freezing has progressed to the proper time, switch 33 closes. This starts timer 4S and operates relay 54, which in turn closes valves 5, 8, and 11 and shuts off the water pump 17, and opens valves 13, 15 to start the thaw 7 Relay 41 now they are cut to size, drop onto plate 22, and are directed to bin 25. The holding circuits for the relays keep these relays energized when switch 33 (or 34) opens during the thawing phase. At the proper interval timer 43 opens switches 49, 53 to deenergize the timer and deenergize relays 54, 55, 35 and 41, but the timer immediately closes switches 49, 53 so that the system is reenergized to start a new freezing cycle. (However, should both switches 31, 32 be open, caused by bins 25, 27 being filled, the system is not reenergized, but is put in condition so that closing of a switch 31 or 32 will reenergizc the system.)

When the cube ice bin is filled switch 31 is opened, so that at the completion of the thawing phase when the timer closes switches 49, 53, relay 35 remains deenergized. In this position, closing of switch 32 energizes relay 41 to start operation. As switch 33 is deenergized, only switch 34- can start the thawing, and as this switch 34 operates at a shorter freezing time it allows the production of thinner wall ice rods. The closing of switch 3 energizes relay 54 to start the thawing phase, as before described, and as relay 35 remains deenergized, the current for starting motor 21 will pass by lead 78 through switch 70 at position d, wire 8%, coil 75, wire 79, switch 77 at position 1 and wire 62, and the motor 21 will be started in the reverse direction to produce crushed ice.

Under manual control either switch S2 or 83 is opened. With switch 33 open and switch 82 closed the apparatus will produce cube ice until bin 25 is filled and then will stop operating. With switch 82. open and switch 83 closed, the apparatus will produce crushed ice till bin 27 is filled and then will stop operating.

When the apparatus is on manual control during the crushed ice cycle and switch 82 is closed andswitch 83 is opened, two efiects are possible depending on whether, when switch 33 is opened, the apparatus is on the thawing or freezing phase. It on the thawing phase, the energization of relay 35 by closing switch 82 has no effect on motor 21, as coil 75 has been cut out by the centrifugal switch, so the ice is crushed. However, the subsequent freezing cycle is placed under control of switch 33 to produce cube ice. On the other hand, if switch 32 'is closed and switch S3 is opened during the freezing phase of a crushed ice cycle, switch 3 3 is cut out and switch33 is cut in so tr e freezing time is lengthened .to produce cube ice.

hen the apparatus'is on the cube ice cycle and switch 83 is closed and switch 82 is opened, the machine will continue with the cuheice cycle because relay 35 remains energized, the subsequent freezing cycle is placed under control of switch 34 to produce crushed ice.

it will be understood that although i have shown the invention applied in conjunction with a reversible cuttercrusher, the invention may be applied to a separately controlled cutter or crusher in the same manner.

I claim as my invention:

1. in an ice making machine comprising a pair of ice storage bins, said machine operating on alternatefreezing and thawing phases and being arranged to selectively direct ice to said bins: an automatic control circuitincluding operation starting and terminating switches for said machine; a first means maintained in inoperative position by predetermined fullness of one of said ice bins and responsive to a depleted condition of said one binto operate the starting switch'to starting position toinitiate operation of said machine; a second means maintainedin inoperative position by predetermined fullness of the other of said ice bins and responsive to a depleted condition of said other ice bin and operating alternatively with the first means to operate said starting switch to starting position; and a third means actuated at the end of the thawing phase to operate said terminating switch to stopoperation of said machine when said first and second means both are in inoperative position.

2. in an icemaking machine: a storage binforsized ice; a storage bin for crushed ice; said machine operating on alternate freezing and thawing phases and arranged to selectively produce sizedice and crushed ice and direct sized and'crushed ice to the corresponding bin: an automatic control circuit including operation starting and terminating switches for said machine;.a first means maintained in inoperative position by predetermined fullness of said sized ice bin and responsiveto a depleted condition of said sized ice bin to operate the starting switch to starting position to initiate operation of said machine; a second means maintained in inoperative position by predetermined fullness of said crushed ice bin and responsive to a depleted condition of saidcrushed ice bin and operating alternatively with'the first means to operate said starting switch to starting position; means controlled by one of said first or second means to selectively operate said machine to produce sized or crushed ice for the corresponding bin; anda third means actuated at the end of the thawing phase to operate said terminating switch to stop operation ofsaid machine when said firstand second means both are in inoperative position.

3. in an ice making machine: a storage bin for sized ice; a storage bin for crushedice; said machine operating on alternate freezing and thawing phases to produce and release ice rods; areversible severing device to sever said ice rods selectively into sized or crushed ice depending on the directionof operation thereof and to direct sized or crushed ice .to the corresponding bin; an automatic control circuit including operation starting and terminating switches for saidmachinqa first means maintained in inoperative position by predetermined fullness of one of said ice bins and responsive to a depleted condition of said one bin to operate thestarting switchto initiate operation of said machine; a second means maintained in inoperative position by predetermined fullness .of theother of said ice bins and :responsive'to ,a-depleted condition of said other ice binand operating alternatively and conjointly with the first means to-operate said'starting switch to starting positioma fifth means selectively controlled by one of said first .or.;second means todeterrnine the direction of operation of said severing device and direct the ice produced to the corresponding bin; and a third means actuated atthe end of ,thethawing phase to operate said terminating switch and-stop operation of said machine when said first and second means both are in inoperative position.

4. An apparatuses specified in claim 1 having a pair of members operative in sequence to terminate the freezing phase at different lengths of operating time; and wherein one of saidfirst and second means selectively renders operative one of said pair of members to correspondingly varythe freezing phase time.

5. An apparatus as specified in claim 4 wherein: said ice making machine includes a reverse cycle evaporator operating on alternatefreezingand thawing phases; and said pair ofmembersare switches controlled by the pressure in .the evaporator.

6. .An apparatus asspecifiedin claim Zhaving: a pair of members vto-terminate the freezing phaseat different lengths of operating time, and wherein said first means in its operative andinoperative positions selectively renders operative oneof said pair of members to correspondingly vary .the freezing phase .time.

7. An ice making machine as specified in claim 1 wherein: said third means is a timer; .and having a fourth means responsive tothe ending of the freezing phase for energizing said timer.

.8. An icemaking machine as specified in claim 7 including: a holding circuit for the .timer energized by said fourth means; said-terminatingswitch being in the timer energizing. and holding circuits.

9. .A reverse'cycle ice making machine comprising: an evaporator operating on alternate freezing and thawing phases to produce and release ice masses; a pair of ice storage bins for receiving ice from said machine; cycle control means for said evaporator to shift the operation are in inoperative position.

pleted bin.

chances thereof between thawing and freezing phases; a second means to actuate said cycle control means when a predetermined thickness of ice has been formedto shiftthe operation of the evaporator to the thawing phase; a third 'means to actuate said cycle control means when a different predetermined thickness of ice has been formed to shift the operation of the evaporator to the thawing phase;

' a compressor, an evaporator and a pair of ice storage bins, said machine operating on alternate freezing and thawmgphases and arranged to selectively direct ice to said bins: an automatic control circuit including a relay 'forjclosing a starting switchfor the compressor in energized position; operating circuit for said relay including a first means maintained in inoperative position by predetermined fullnes's'of one of said bins and responsive to a depleted condition of .said one bin to operate said relay to close the starting switch and a second means maintained in inoperative position by predetermined fullness of the other of said bins and responsive to a depleted condition of said other bin to operate said relay to close :the Starting switch; a terminating switch in said relay o gcrating circuit; and means actuated at the end of the thawing phase to open said terminating switch to deenergize the relay and then close the terminating switch whereby said relay circuit is maintained ready to be ener gized by one of said first and second means.

11. In an ice'making machine comprising a plurality of ice storage bins, said machine operating on alternate freezing and thawing phases and being arranged to selectively direct ice to said bins; a plurality of means each associated with one of said bins respectively and each maintained in inoperative position by predetermined fullcondition of said respective bin to start operation of said machine; and a third means actuated at the end of the thawing phase to stop operation of said machine when all said means associated with said bins are in inoperative position. a

, 12. In an ice making machine comprising a plurality ofice storage bins, said machine operating on alternate freezing and thawing phases and being arranged to selectively direct ice to said bins; an automatic control circuit including operation starting and terminating switches for said machine; a plurality of means each associated with one of said bins respectively and'each maintained in inoperative position by predetermined fullness of said respective bin and responsive to depleted condition of said respective bin to operate the starting switch to starting position toinitiate operation of said machine; and a third means actuated at the end of the thawing phase to operatesaid terminating switch andstop operation of said machine when all said means associated with said bins 13. In combination withan ice making machine operating on alternate freezing and thawing phases to produce masses of iceduring the freezing phase and discharge said ice masses during the thawing phase: means for selectively reducing the discharged ice to different size types; a plurality of ice storage bins for respectively receiving and storingice of one'selected sizetype from said reducing means; and a plurality of means, each associated with one of said bins respectively and each reness of said respective bin and responsive to depleted V first reducing means to produce one size type ice, and in 1 sponsive to depleted condition of said respective bin to automatically selectively actuate said ice reducing means to produce the size type ice 'correspondingto said de- 14. The combination as specified in claim 13 wherein: said means for selectivelyredu'cing the discharged'icc comprises a reversible member forming one size type when operating in one direction, and another size type when operating in reverse direction; and said means associated with said bins automatically selectively actuates said reducing means in the direction to produce the ice size type as therein'specified. 15. An ice making machine combination as specified in claim 13 having: freezing phase terminating means operative at different lengths of operating time; and

wherein said means associated with said bins cooperates with said freezing phase terminating means to vary the lengt'ri of time of. the freezing phase to correspond with V the selection of size type ice for the depleted bin.

16. In combination with an ice making machine operating on'alternate freezing and thawing phases to produce masses of ice during the freezing phase and discharge said ice masses during the thawing phase: a first reducing means for reducing the discharged ice masses into bodies of a firstsize type; a second reducing means for reducing the discharged ice masses into bodies of a second size type; a first ice storage bin for receiving and storing ice from said first reducing means; a second ice storage bin for receiving and storing ice from said sec- 7 operating time; and wherein said means associated with said bins selectively renders inoperative one of said pair of members to allow the other operative one of said pair to terminate the freezing phase at a time corresponding to the selected reducing means.

18. An ice making machine combination as specified in claim 17 having: main means to energize and deenerw gize said ice making machine; and means to terminate the thawing phase and operate said main means momentarily to deenergize said machine; said means associated with said bins operating said main means in cooperation with said thawing phase terminating means in response to depleted condition of one of said bins to energize said machine.

19. An ice making machine as specified in claim 16 wherein: said means associated with said bins includes a selector relay which in energized position actuates said deenergized position actuates said second reducing means to produce another size type ice.

20. In combination with an ice making machine operating on alternate freezing and thawing phases to produce ice during the freezing phase and discharge said ice dur 'ing the thawing phase to selective ice reducing means for to produce the size type ice corresponding to said depletedbin; and means operative at completion'of the thawing ph ase for stopping said machine when .all said plural means associated with said bins are in inoperative position. 7

21. In combination with an ice making machine operating on alternate freezing and thawing phases to produce ice masses during the freezing phase and. discharge said' ice masses during the thawing phase and having phase control means responding to the thickness of ice masses formed in the freezing phase for initiating the thawing phase: reducing means to reduce ice discharged from said machine into a plurality of type sizes; a plurality of ice storage bins corresponding to the plural type sizes; means to direct the type size of ice to the corresponding storage bin; and means associated with said respective bins responsive to depleted condition of one of said bins to automatically actuate said directing and reducing means to produce the corresponding type of ice for said depleted bin.

22. In an ice making machine: a storage bin for sized ice; a storage bin for crushed ice; said machine operating on alternate freezing and thawing phases to produce and release ice rods; a reversible severing device to sever said ice rods selectively into sized or crushed ice depending on the direction of operation thereof, and to direct sized or crushed ice to the corresponding bin; a first means maintained in inoperative position by predetermined fullness of one of said ice bins and responsive to a depleted condition of said one bin to initiate operation of said machine; a second means maintained in inoperative position by predetermined fullness of the other of said ice bins and responsive to a depleted condition of said other ice bin and operating alternatively with the first means to initiate operation of said machine; means selectively controlled by one of said first or second means to determine the direction of operation of said severing device and direct the ice produced to the corresponding bin; and means actuated at the end of the thawing phase to stop operation of said machine when said first and second means both are in inoperative position.

Reierences Cited in the file of this patent UNITED STATES PATENTS 2,239,234 Kubaugh Apr. 22, 1941 2,396,308 Williams Mar. 12, 1946 2,444,514 Kubaugh July 6, 1948 2,526,262 Munshower Oct. 17, 1950 2,549,747 Leeson Apr. 17, 1951 2,595,588 Lee et al May 6, 1952 2,645,910 Leeson July 21, 1953 2,648,203 Heuser et a1 Aug. 11, 1953 

